Circuit board card cage with one-piece, integral card guide units

ABSTRACT

A card guide unit for use in guiding and positioning circuit boards in a card cage, which guide unit is integral, having front and rear cross members that are integral with machined elongated card guides, having machined spaces between the card guides, and which guide units are inter-connectable to side walls of a card cage, providing identical precisioned alignment between circuit boards in the card guides so that precise electrical connections can be made between the circuit board and electrical connectors on the back plane.

[0001] This is a continuation-in-part application from co-pendingapplication Ser. No. 09/109,485 filed Jul. 2, 1998.

BACKGROUND OF THE INVENTION

[0002] This invention concerns a new and improved one-piece, integralcard guide unit for use in guiding and supporting circuit boards in acircuit board card cage. Circuit board card cages are well known. Thegeneral structure of such a card cage is shown and described and thepublication VME Bus Specification Manual, Rev. c.1, Oct. 1995, pages215-247 of this publication by Motorola entitled “Series in Solid-StateElectronics Rev. c.1; which publication is also entitled “The VME BusSpecification” dated Oct. 1995. This VME Bus Specification Manual alsois known as the “IEC 821 Bus” and the “IEEE P1014/d1.2,” and was printedby Printex Publishing, Inc.

[0003] Such circuit board card cages generally comprise enclosureshaving side walls and a back plane, secured together in a frame thatcomprises elongated front and rear cross members connected to the uppersurface of the side walls and back plane and to the lower surface of theside walls and back plane, to form the circuit card rack enclosure. Thisenclosure is often open in the front, top and the bottom to allow aircirculation around the individual circuit boards to cool the electroniccomponents. The top and bottom and front openings can be closed ifdesired.

[0004] Positioned within the card cage structure are card rails orguides that extend generally between the front and rear cross members.These card guides have grooves that are opposing between the lower andupper card guide rails, for receiving the edges of the circuit boards.The card guides are also laterally spaced from each other, to providespace between the electrical and electronic components secured to thecircuit boards. At the end of the known circuit boards, there is anelectrical connection that interconnects with an electrical connectionon the rear panel, known as the back plane electrical connector. Thecard rails in these card cages are often individually located andsecured to the front and rear cross members in a manner to provide avertical orientation of the circuit board to align the electricalconnection on the circuit board with the electrical receptacle on theback plane. Here, problems arise in that the card rails often becomeskewed, moved or twisted by vibration or in the general use of the cardcage, which can include shocks received by the card cage or just theoverall use of the card cage in the environment in which the card cageis located. Such occurrences cause the circuit board to becomemisaligned to the extent that a good easy straight forward and preciseconnection cannot be made to the electrical circuit on the back plane.Further, in many card cages, the structure of the card rails and indeedthe card cage in general is made of light sheet metal type constructionor of plastic or other suitable materials. In these assemblies, there isa weak or insufficient connection between the card rails and the crosssupport members that will prevent slight movements or skewing of some ofthe card rails relative to other card rails which skews the position ofthe circuit boards. There are also some card guides units that areconnected to the cross members in a manner where it is possible for thecard guides to move relative to the cross member. This skews the circuitboard in the guide relative to the opposing card guide, which again hasan adverse effect on the circuit board being able to make the correctelectrical connection.

[0005] So, there is a definite need for a new and improved circuit boardcard guide rail in which the card guide bars are integral with themultiple cross members, so that identical card rack guide units areconnectable to the side walls and back plane of the card cage. Thisprovides precise alignment of the circuit board with the back planeelectrical connections, is not subject to twisting and other movementsbetween the card guides and the cross members, and which card guides areformed in a manner that allows some transitory tolerance to twisting,vibration and other shocks to the card cage, while still maintainingpermanent, precise alignment of the circuit board with the back planeelectrical connections.

SUMMARY OF THE INVENTION

[0006] This invention concerns a new and improved one-piece, integralcircuit card guide unit. This new circuit card guide unit is preferablymade of metal. All parts, including the front and rear cross members andthe elongated card guides, are all made in one integral unit. The newand improved construction of this guide unit provides a strong integralstructure that when mated with an identical guide unit, in opposedrelationship, and secured between two side walls at the outer ends ofthe respective cross members, provides a card rack in which the circuitboards or cards are directly aligned with the back plane electricalconnection, and the integral construction holds this precision alignmentthrough use of the card cage in many environments. This integralstructure, which is preferably made of aluminum, is extruded to providethe cross members. An interconnecting portion of the aluminum plate isthen machined to provide the precision elongated card guides with aU-shaped recess, that is rigidly and integrally secured in positionrelative to the rest of the rack unit. In the shaping of the elongatedcard guides, the metal content therein is reduced to that required tomaintain the rigidity and functionality of the card guides, while stillallowing slight flexing as may be advantageous in aligning the circuitboards with the electrical contacts on the back plane. Further,elongated, longitudinal, U-shaped card guides of protective insulatedmaterial can e snapped into or fitted into the U-shaped recesses in thecad guide for receiving, guiding and positioning the respective outeredges of the circuit boards.

[0007] This invention eliminates the problems of prior devices by theintegral connection between the ends of the card guides and the crossmembers. The problems with these connections become major in prior artdevices, because regardless of the connection that is made, thisconnection still allows movement of the card guides relative to thecross members and thus relative to the electrical connections on theback plane. Also, since this invention is not just an extruded product,it can be machined to required tolerances to achieve the desiredrigidity and strength, with the desired reduction of weight andnon-flexibility. Further, since each of the rack units are identical,the problems encountered in having different sizes, or different shapes,or different length ends of the cross members, all of which affects thealignment of the opposing card guides when installed in a card cage, areeliminated.

[0008] It is therefore an object of this invention to provide a new andimproved card guide unit.

[0009] It is another object of this invention to provide a new andimproved integral card cage rack unit that is machined to closetolerances for lasting, precision alignment of circuit boards with theback plane electrical connections.

[0010] It is another object of this invention to provide a new andimproved integral card cage rack unit, that in combination with knowncircuit board card cages having two side walls and a back plane, providea new and improved overall card cage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of the extrusion from which the cardguide is machined;

[0012]FIG. 2 is an enlarged perspective view of the machined card guide;

[0013]FIG. 3 is a further enlarged top plan view of the card guide;

[0014]FIG. 4 is a front view of the card guide as shown in FIG. 3;

[0015]FIG. 5 is an enlarged sectional view taken on line 5-5 of FIG. 3;

[0016]FIG. 6 is a sectional view taken on line 6-6 of FIG. 4;

[0017]FIG. 7 is a sectional view taken on line 7-7 of FIG. 4;

[0018]FIG. 8 is a side view of a typical card cage cabinet incorporatingtop and bottom card guides of the present design;

[0019]FIG. 9 is a front view of one end of the card cage; and

[0020]FIG. 10 is an enlarged sectional view taken on line 10-10 of FIG.9, showing the simple assembly of the complete card cage structure.

[0021]FIG. 11 is similar to FIG. 6, but showing an insulated insert inthe channel.

[0022]FIG. 12 is an enlarged sectional view taken on line 12-12 of FIG.11.

[0023]FIG. 13 is a sectional view taken on line 13-13 of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] The present invention will be better understood from thefollowing detailed description of a preferred embodiment of theinvention, taken in conjunction with the accompanying drawings in whichlike reference numerals refer to like parts and in which:

[0025] An exemplary embodiment of the circuit board and card cage withone-piece, integral card guide units, is illustrated in accordance withthe invention in FIGS. 1 through 10. Referring to FIG. 2, the circuitboard card guide unit 12 has a pair of cross members 14 and 16, member14 being the rear cross member and member 16 being the front crossmember. Interconnecting the two cross members 14 and 16 are integralelongated circuit board card guides 18 that have a generally rectangularcross section with a unshaped card guide channel 28 in the upper surfaceof the guide. An enlarged entry to channel 28 is formed by angledsurfaces 34 that aid in guiding the circuit board card edge into theU-shaped channel 28. The end portions 20 of each of the bar card guides18 are integrally connected to the upper surface 30 of each of therespective cross members. The underneath or lower surface 38 of eachcard guide 28 has a curved surface, see FIGS. 5 and 7, which surface isabove the upper surface 30 of the respective cross members 14 and 16.The intersection of the lower curved surface of the card guides 18 tothe surface 30 by portion 20, has a groove 26 that connects the roundedsurface 38 to the flat surface 30. Groove 26 also provides a degree offlexibility to the rigid card guide structure permitting some slighttorsional movement on guides 18 in the rigid, integral structure of theentire card guide unit, that aids in absorbing vibrations and makingcircuit board electrical connections.

[0026] Referring to FIGS. 11, 12 and 13, a U-shaped, elongated,longitudinal card guide insert of protective insulated material 150 isselectively inserted into the U-shaped channel 28 for receiving,positioning and guiding circuit boards 158. This longitudinal card guide150 may be made of plastic or other suitable materials. Its purpose isto provide a protective recess that acts to protect side movement of theedge of the circuit board 158 in recess 151. The card guide insert doesnot grip or squeeze against the sides of the circuit board and the innersides of the U-shaped channels are wider than the thickness of thecircuit board. This protective card guide insert also functions toinsulate or protect circuit tracings 160 or the like that may besufficiently close to the edge of the circuit board as to requireinsulating protection. This protective card guide 150 has split pinsthat fit into holes 154 that secure the protective card guide in asnapped-in position while allowing easy replacement or insertion foruse, if desired, or to replace worn protective card guides. The cardguide 150 has slots 156 adjacent each side of the pins 152 thatfacilitate the forming of the pins 152. The insert card guide 150extends the full length of the U-shaped, longitudinal card guide recess28. This protective insulated card guide further enhances the protectionof the entire integral card guide unit in absorbing vibrations in itsnormal operation in coordination with the integral card guide unit.

[0027] Each of the cross members 14 and 16 have forward slots in oneside of the cross members that extend the full length of the member, anda rear slot 24 that extends the full length of the cross members. Bothslots 22 and 24 provide means for interconnecting the ends of therespective cross members to the side walls of a card cage, such as theside wall illustrated in FIGS. 8 and 9, namely side walls 102, 104 andback wall 106.

[0028] In installing the card guide units 12 into a known card cage, seeFIGS. 8 and 9, the card cage has side wall 102, see FIGS. 8 and 9, andopposing side wall 103, see FIG. 10, that are secured to the endsurfaces of cross members 16 and 14, by screws 122, that are insertedinto the ends of the channels 23 in slot 22, see FIG. 10. The back plane106 is connected to the rear cross member 14 by screws or bolts thatpass through threaded holes in a long longitudinal strap 18 that has alength corresponding to the length of the slots. The bolt 140 passesthrough the back plane 106 and washer 138 to threaded holes in strap 118to secure the back plane 106 in position. An electrical conduit and backplane stiffener 108 is secured to the back plane 106 by the longitudinalstraps 118 in channels 127 and the threaded bolts 116. Electricalconduits or similar devices can pass through the conduit 119 in thenormal manner, to the back plane electrical contacts. Once the card cageends are bolted and secured into position, the cards are moved throughthe channels 28. The circuit board or card then makes electrical contactwith electrical connections on the back plane 110.

[0029] The circuit board card 111 in moving in the channels 28 can bepositioned relative to the front surface of stiffener 108. A door orsimilar type front panel 102 can be secured to the front side surfacesof the front cross member 116. This is accomplished by a longitudinalstrap 118 in slots 22 with threaded holes therein that receive thethreaded bolts 139. A buffer 120 of some type can be secured to thefront cover 102, which can press against the end surface of the circuitboard 111 holding the circuit board 111 into electrical contact with theelectrical connections in the back plane 110.

[0030] The method, form and procedure for making the integral singlepiece card guide involves the first step of extruding the structure 10into the form illustrated in FIG. 1. The extrusion forms the integralcross member portions, front and rear and the plate section 11 asillustrated, while at the same time forming slots 22 and 24, groove 26and the upper surface 30 of the respective front and rear cross members.The entire structure 11 of the part 10 is flat and aligned at the edgeswith the end surfaces of the cross members. The part 10 is then milledor machined to cut away the metal, such as aluminum, leaving theindividual card guides 18 as illustrated in FIG. 2. This machining alsocuts the u-shaped channels 28 into the bar 18, and the widened entry 34into the guide channels 28. The metal between the respective card guidemembers 18 is removed and the flat surfaces 30 expanded to provide theopen space between the card guides 18. This maximizes the opening space36 to that between the side surfaces of the respective card guides andthe upper flat surfaces of the respective cross members 14 and 16. Athin plate 39 can be slidably inserted, or if flexible, bent to bere-inserted in slots 24 to cover the open space 36, where this isdesired.

[0031] In Operation

[0032] The one-piece integral card guide units are formed in the mannerillustrated and described in FIGS. 1 and 2. The card guide is thensecured in the manner recited between side walls 102 and 103, see FIGS.8, 9 and 10, by screws 114 so that the side walls 102 and 103 fitdirectly against the ends of the cross members. The back plane 106 isconnected by screws or bolts 140 to the rear side of the respectivecross members 14 in the manner described. The back plane electricalconnectors 110 are positioned in alignment with the channel guides 28.Circuit cards are then slidably positioned in the grooves 28 of therespective card guides with the end of the circuit board card makingelectrical contact with the back plane electrical connectors. A frontpanel 104 can then be mounted to the front side surfaces of the frontcross members 16 in the manner illustrated. The circuit board card isthen in a position for electrical operation and the assembly iscomplete.

[0033] It can be understood that the one-piece integral card guide unitsare identical, have the same identical lengths and widths andaccordingly when the upper card guide unit and the lower card guideunits are directly aligned, the card guides are identically positionedand aligned to the electrical connections in the back plane, and areintegral to the respective cross based members. It is further understoodthat this provides for precise alignment of the circuit board in thechannels 28, which alignment is less likely to be disturbed by impact,shock, vibration or other causes that could interfere or change theposition of the circuit card in the channels relative to the crossmembers, as illustrated and described.

[0034] It should be further recognized that changes may be made in theform, construction, and arrangement of the circuit board card cage withthe one-piece integral card rack unit as described herein withoutdeparting from the spirit and scope of the invention and withoutsacrificing any of its advantages, and it is understood that all mattersherein are to be interpreted and illustrative and not in any limitingsense.

We claim:
 1. A one-piece, integral card guide element for guiding andsupporting circuit boards in a card cage comprising: an integral metalguide element having integral, unitary, spaced, and opposing front andrear cross members, with each member having upper and lower surfaces andinner and outer surfaces; a plurality of spaced, metal elongated cardguides with respective ends integrally joined to said cross members,said guides extending between said front and rear cross members; each ofsaid card guides having therein an integral guide channel for guidingand positioning circuit boards; said ends of said card guides areintegrally joined to said upper surfaces of said front and rear crossmembers; said card guides being aligned in spaced positions along thelength of said cross members, with open space between each of said cardguides; and said card guide unit being made from one piece of metal sothat no inner movement occurs between said card guides and said crossmembers.
 2. Integral card guide units for guiding and supporting circuitboards in a card cage having inner side walls and a back wall in thecard cage with circuit connections comprising: integral card guideelements, each having a pair of spaced opposing metal front and rearcross members with upper and lower surfaces; a plurality of spaced metalelongated card guides having ends integral with said cross members andextending between said front and rear cross members, each of said cardguides having a channel for guiding and positioning circuit boards in acard cage, each of said card guides being aligned along the length ofsaid cross members with open spaces between said card guides, extendingto said cross members, said cross members having slots for securing saidintegral guide units to side walls in said card cage, with one of saidguide units being inverted relative to another guide unit and said cardguides being aligned to receive the upper and lower edges of a circuitboard, each of said integral guide units being identical, said guideunits are in exact alignment through connections to the card cage sidewalls, wherein the circuit connections on the circuit boards are alignedfor precise contact with circuit connections on the back plane of theback wall of a card cage, and second longitudinal card guide of U-shapedinsulated material fitted into each guide channel for receiving andpositioning circuit boards.
 3. A method for forming a one-piece,integral card guide unit for guiding and supporting circuit boards in acard cage comprising the steps of: forming the card guide unit byextruding material to form a pair of spaced opposing front and rearcross members with upper and lower surfaces, and a flat memberintegrally connected to the upper surface of each of said spaced crossmembers and extending there between, said extruding step extruding slotsin the outer and inner surface of each of said cross members, andmachining a plurality of spaced elongated card guides in said flatmember, with each card guide having channels in their upper surface, andsaid card guides being spaced along the length of said cross members atnormal angles and having an open space between each of said card guides,that extends along the length of said card guides, to the said crossmembers.